ERC-8004: Agent Trust Protocol

{
  "type": "https://eips.ethereum.org/EIPS/eip-8004#registration-v1",
  "name": "Example Rates API",
  "description": "FX rates for Mento stablecoins, priced per request",
  "image": "https://example.com/logo.png",
  "services": [
    {
      "name": "web",
      "endpoint": "https://example.com"
    },
    {
      "name": "MCP",
      "endpoint": "https://example.com/mcp",
      "version": "2025-06-18"
    },
    {
      "name": "A2A",
      "endpoint": "https://example.com/.well-known/agent-card.json",
      "version": "0.3.0"
    }
  ],
  "x402Support": true,
  "active": true,
  "supportedTrust": ["reputation"],
  "registrations": [
    {
      "agentId": 12345,
      "agentRegistry": "eip155:42220:0x8004A169FB4a3325136EB29fA0ceB6D2e539a432"
    }
  ]
}

import {
  createPublicClient,
  createWalletClient,
  http,
  parseEventLogs,
} from 'viem';
import { privateKeyToAccount } from 'viem/accounts';
import { celo } from 'viem/chains';

// Celo mainnet (42220), Identity Registry
const identityRegistry =
  '0x8004A169FB4a3325136EB29fA0ceB6D2e539a432';
const abi = [
  {
    type: 'function',
    name: 'register',
    stateMutability: 'nonpayable',
    inputs: [{ name: 'agentURI', type: 'string' }],
    outputs: [{ name: 'agentId', type: 'uint256' }],
  },
  {
    type: 'event',
    name: 'Registered',
    inputs: [
      { name: 'agentId', type: 'uint256', indexed: true },
      { name: 'agentURI', type: 'string' },
      { name: 'owner', type: 'address', indexed: true },
    ],
  },
] as const;

// This key's address is minted the NFT and
// published as the agent's wallet
const key = process.env.PRIVATE_KEY as `0x${string}`;
const account = privateKeyToAccount(key);
const publicClient = createPublicClient({
  chain: celo,
  transport: http(),
});
const walletClient = createWalletClient({
  account,
  chain: celo,
  transport: http(),
});

const { request } = await publicClient.simulateContract({
  account,
  address: identityRegistry,
  abi,
  functionName: 'register',
  args: ['https://example.com/agent.json'],
});

const hash = await walletClient.writeContract({
  ...request,
  // Celo mainnet (42220), USDC fee-currency adapter.
  // USDC has 6 decimals, so feeCurrency takes the
  // adapter address, not the token address. Omit
  // this field to pay gas in CELO.
  feeCurrency: '0x2F25deB3848C207fc8E0c34035B3Ba7fC157602B',
});

const receipt =
  await publicClient.waitForTransactionReceipt({ hash });
const [registered] = parseEventLogs({
  abi,
  eventName: 'Registered',
  logs: receipt.logs,
});
console.log('Registered as agent', registered.args.agentId);

import {
  createPublicClient,
  createWalletClient,
  http,
  zeroHash,
} from 'viem';
import { privateKeyToAccount } from 'viem/accounts';
import { celo } from 'viem/chains';

// Celo mainnet (42220), Reputation Registry
const reputationRegistry =
  '0x8004BAa17C55a88189AE136b182e5fdA19dE9b63';

const abi = [
  {
    type: 'function',
    name: 'giveFeedback',
    stateMutability: 'nonpayable',
    outputs: [],
    inputs: [
      { name: 'agentId', type: 'uint256' },
      { name: 'value', type: 'int128' },
      { name: 'valueDecimals', type: 'uint8' },
      { name: 'tag1', type: 'string' },
      { name: 'tag2', type: 'string' },
      { name: 'endpoint', type: 'string' },
      { name: 'feedbackURI', type: 'string' },
      { name: 'feedbackHash', type: 'bytes32' },
    ],
  },
] as const;

const key = process.env.PRIVATE_KEY as `0x${string}`;
const account = privateKeyToAccount(key);
const publicClient = createPublicClient({
  chain: celo,
  transport: http(),
});
const walletClient = createWalletClient({
  account,
  chain: celo,
  transport: http(),
});

const hash = await walletClient.writeContract({
  address: reputationRegistry,
  abi,
  functionName: 'giveFeedback',
  args: [
    9699n,                   // example agentId - this rates a real agent
    85n,                     // value, int128
    0,                       // valueDecimals
    'starred',               // tag1: category
    '',                      // tag2: optional
    'https://example.com',   // endpoint used
    '',                      // feedbackURI: none, so no content to hash
    zeroHash,                // keccak256 of the content at feedbackURI
  ],
});

await publicClient.waitForTransactionReceipt({ hash });

import { createPublicClient, formatUnits, http } from 'viem';
import { celo } from 'viem/chains';

// Celo mainnet (42220), Reputation Registry
const reputationRegistry =
  '0x8004BAa17C55a88189AE136b182e5fdA19dE9b63';

const abi = [
  {
    type: 'function',
    name: 'getClients',
    stateMutability: 'view',
    inputs: [{ name: 'agentId', type: 'uint256' }],
    outputs: [{ name: '', type: 'address[]' }],
  },
  {
    type: 'function',
    name: 'getSummary',
    stateMutability: 'view',
    inputs: [
      { name: 'agentId', type: 'uint256' },
      { name: 'clients', type: 'address[]' },
      { name: 'tag1', type: 'string' },
      { name: 'tag2', type: 'string' },
    ],
    outputs: [
      { name: 'count', type: 'uint64' },
      { name: 'value', type: 'int128' },
      { name: 'valueDecimals', type: 'uint8' },
    ],
  },
] as const;

const publicClient = createPublicClient({
  chain: celo,
  transport: http(),
});

const agentId = 9699n; // example agentId
const clients = await publicClient.readContract({
  address: reputationRegistry,
  abi,
  functionName: 'getClients',
  args: [agentId],
});

// getClients returns everyone who has ever rated this agent. Anyone can call
// giveFeedback, so for a decision that matters, replace this with the reviewer
// addresses you already trust and treat getClients only as a starting point.
//
// Two guards, because two different cases come back empty:
// 1. clients.length === 0: nobody has rated this agent, and getSummary
//    would revert with "clientAddresses required", so skip the call.
// 2. count === 0n after the call: the agent has feedback, but none with
//    this tag, so the filtered summary is empty.
if (clients.length === 0) {
  console.log('No starred feedback yet');
} else {
  const [count, value, decimals] =
    await publicClient.readContract({
      address: reputationRegistry,
      abi,
      functionName: 'getSummary',
      // Always pass a tag. Averaging across tags mixes ratings with
      // unrelated feedback, and the result means nothing.
      args: [agentId, clients, 'starred', ''],
    });

  if (count === 0n) {
    console.log('No starred feedback yet');
  } else {
    console.log(`${count} reviews, score ${formatUnits(value, decimals)}`);
  }
}